The present invention relates to an apparatus for joining two abutting rod-shaped articles by convoluting a uniting band around their juncture. In particular, this invention relates to a device for applying an adhesive-coated band of tipping or similar paper around two co-axial rod-shaped articles which constitute a filter rod and tobacco rod.
There are several types of devices known in the prior art which are used to assemble a filter rod and a tobacco rod together by a uniting band. Although these devices have been used for many years and are still used in some instances, there are numerous difficulties with their operation which cause a considerable amount of downtime for an assembly machine.
One of the assembly apparatus used includes a roll drum which has a plurality of raised pockets around its periphery. Normally, as the roll drum is rotated in a counterclockwise direction, a double filter rod and tobacco rod abutting each end of the filter rod are placed on the rear side of the raised pockets as the pockets pass near a transfer drum. While on the transfer drum, a tipping band or flag which has an adhesive coating is secured at one point to the outer surface of the filter so that, when transfer to the roll drum is made, the flag will be in contact with the surface of the roll drum. The roll drum has vacuum ports between the raised pockets to hold the flag against the drum.
Immediately adjacent the transfer point and contiguous to the surface of the roll drum is a rolling hand or plate which contacts the periphery of the filter and tobacco rods, causing them to roll in the direction opposite the direction of rotation of the roll drum. The rods are rolled by the hand slightly more than one revolution so that the tipping band overlaps and the double cigarette formed will rest against the forward side of the adjacent trailing raised pocket. The double filter cigarette then passes under a guide rail adjacent the surface of the drum which holds the double cigarette on the drum until transferred.
It has been found that the major problems with this type of rolling apparatus is the inability to purge the system of bad work (cigarettes which have burst, misaligned rods at transfer, and trash such as paper, adhesive and tobacco) because the roll hand engages the rods immediately adjacent transfer. The positive contact of the rods by the raised pockets and roll hand at transfer cause the misaligned rods and bad work to be carried around the drum and, oftentimes, jam-ups are caused. Loose tobacco, paper, adhesive and other substances used in forming the ciagrettes tend to build up on the roll hand causing the gap or spacing from the drum to be changed. Since this spacing is very critical to properly form the cigarettes, it becomes necessary to clean the roll hand frequently and reset the proper gap.
To overcome this problem, the above-described rolling apparatus was modified and this modification is disclosed in U.S. Pat. No. 3,527,234. Basically, the modified device utilizes a roll drum with a shallow recessed pocket having a vacuum holding system. This device differs from the first described device in that the roll blocks or hand is spaced from the point of transfer and the vacuum system exclusively is used to transfer and hold the rods to the roll drum. The spacing between the roll block and the transfer point and the exclusive use of the vacuum to hold the work on the drum provide an area where bad work, misaligned cigarettes, etc. can be purged from the roll drum. For example, if the rods are severely misaligned and the vacuum will not pick them up, they will fall off the drum into an appropriate receptacle. Furthermore, by eliminating the roll hand adjacent the transfer point so trash can be purged from the system, there is no trash build-up problem which removes the cause of the improperly formed cigarettes.
While this above-described modification may have eliminated some problems, it produced others. First, since there is no positive control of the rods at transfer, rods which are only slightly misaligned will ofentimes be held on the drum by the vacuum system, causing jam-ups to occur in front of the rolling block. In this particular modification, a switch has been located just prior to the roll block to arrest the machine if a jam should occur. This solution is unacceptable because, each time the machine is shut down, hundreds of properly formed cigarettes are rejected upon restart.
The device disclosed in U.S. Pat. No. 3,527,234 also has an elongated roll block (multi-roll block) whereby the rods are rolled several times. The purpose of the multi-roll was to provide more time for the tipping to adhere to the rods. In order to accomplish this multi-roll, the pockets of the roll drum had to be recessed rather than raised so that the rods can move between several pockets under the roll block. It has been found that the recessed pockets do not provide sufficient control over the cigarettes under the roll block, therefore, they can easily become misaligned. For this reason, a repositioning wheel is required after the rolling block to realign the cigarettes in the pockets. On occasion, the cigarettes become so misaligned that they become crosswise on the drum and the realignment wheel will not realign them so they are not captured in the vacuumized pockets of the drum and will fall off the drum, producing another jam-up possibility.
It has also been found that, because of the recessed pockets, a greater positive pressure has to be placed on the filter and tobacco rods to start them rolling and keep them rolling between pockets. This increased pressure changes the firmness of the filter and the tobacco rod, thus, changing the draft characteristics of the filter and contributing to an already substantial loose end problem (loosely packed tobacco at the end of the tobacco rod).